/* ============================================================
   PDF Viewer – Shared Styles
   Minimal, professional design matching the slides site palette.
   ============================================================ */

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

:root {
  --colour-bg:        #f8f9fa;
  --colour-surface:   #ffffff;
  --colour-heading:   #2c3e50;
  --colour-body:      #34495e;
  --colour-muted:     #7f8c8d;
  --colour-accent:    #3498db;
  --colour-accent-dk: #2980b9;
  --colour-border:    #dee2e6;
  --shadow-card:      0 0 20px rgba(0, 0, 0, 0.08);
  --radius:           6px;
  --max-width:        960px;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto,
               "Helvetica Neue", Arial, sans-serif;
  background: var(--colour-bg);
  color: var(--colour-body);
  line-height: 1.6;
  min-height: 100vh;
}

/* ---------- Layout ---------- */

.page-wrapper {
  max-width: var(--max-width);
  margin: 0 auto;
  padding: 2rem 1.25rem 3rem;
}

/* ---------- Header ---------- */

.site-header {
  margin-bottom: 2rem;
  padding-bottom: 1rem;
  border-bottom: 2px solid var(--colour-border);
}

.site-header h1 {
  font-size: 1.6rem;
  color: var(--colour-heading);
  font-weight: 700;
}

.site-header p {
  margin-top: 0.25rem;
  color: var(--colour-muted);
  font-size: 0.95rem;
}

.breadcrumb {
  margin-bottom: 0.5rem;
  font-size: 0.85rem;
  color: var(--colour-muted);
}

.breadcrumb a {
  color: var(--colour-accent);
  text-decoration: none;
}

.breadcrumb a:hover {
  text-decoration: underline;
}

/* ---------- PDF embed ---------- */

.pdf-container {
  position: relative;
  width: 100%;
  padding-top: 75%;          /* 4:3 aspect ratio default */
  background: var(--colour-surface);
  border: 1px solid var(--colour-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  margin-bottom: 2rem;
}

.pdf-container canvas,
.pdf-container iframe {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  border: none;
}

/* ---------- PDF.js text layer ---------- */
/* Renders invisible but selectable text over the canvas so that
   Hypothes.is (and browser find-in-page) can interact with it. */

.text-layer {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 2;
  overflow: hidden;
  line-height: 1;
  text-size-adjust: none;
  forced-color-adjust: none;
  transform-origin: 0 0;
}

.text-layer :is(span, br) {
  color: transparent;
  position: absolute;
  white-space: pre;
  cursor: text;
  transform-origin: 0% 0%;
}

.text-layer ::selection {
  background: rgba(0, 0, 255, 0.25);
  mix-blend-mode: multiply;
}

/* Hypothes.is highlight styling */
.text-layer .annotator-hl {
  background: rgba(255, 212, 0, 0.3);
  mix-blend-mode: multiply;
}

/* ---------- PDF.js annotation layer ---------- */
/* Renders clickable link regions over the canvas so that hyperlinks
   embedded in the PDF (e.g. URLs added by LaTeX/Pandoc) are interactive. */

.annotation-layer {
  position: absolute;
  top: 0;
  left: 0;
  z-index: 3;           /* above text-layer (z-index: 2) */
  overflow: hidden;
  pointer-events: none;  /* pass clicks through except on links */
}

.annotation-layer a {
  pointer-events: auto;
  display: block;
  opacity: 0;
  transition: opacity 0.15s;
  cursor: pointer;
}

.annotation-layer a:hover {
  opacity: 1;
  background: rgba(52, 152, 219, 0.12);
  border-radius: 2px;
}

/* ---------- PDF list (index page) ---------- */

.pdf-list {
  list-style: none;
}

.pdf-list li {
  margin-bottom: 0.75rem;
}

.pdf-list a {
  display: block;
  padding: 1rem 1.25rem;
  background: var(--colour-surface);
  border: 1px solid var(--colour-border);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  color: var(--colour-heading);
  text-decoration: none;
  transition: border-color 0.15s, box-shadow 0.15s;
}

.pdf-list a:hover,
.pdf-list a:focus-visible {
  border-color: var(--colour-accent);
  box-shadow: 0 0 0 3px rgba(52, 152, 219, 0.15);
}

.pdf-list .pdf-title {
  font-weight: 600;
  font-size: 1.05rem;
}

.pdf-list .pdf-desc {
  display: block;
  margin-top: 0.25rem;
  font-size: 0.85rem;
  color: var(--colour-muted);
}

/* ---------- Comments section ---------- */

.comments-section {
  margin-top: 2rem;
  padding-top: 1.5rem;
  border-top: 1px solid var(--colour-border);
}

.comments-section h2 {
  font-size: 1.2rem;
  color: var(--colour-heading);
  margin-bottom: 1rem;
}

/* ---------- Footer ---------- */

.site-footer {
  margin-top: 3rem;
  padding-top: 1rem;
  border-top: 1px solid var(--colour-border);
  font-size: 0.8rem;
  color: var(--colour-muted);
  text-align: center;
}

/* ---------- Responsive ---------- */

@media (max-width: 600px) {
  .page-wrapper {
    padding: 1rem 0.75rem 2rem;
  }

  .site-header h1 {
    font-size: 1.3rem;
  }

  .pdf-container {
    padding-top: 100%;        /* taller ratio on small screens */
  }
}